Question

Pulp and paper multiple choice questions:

1.What are the following compounds will consume alkaline during kraft pulping

a) lignin, b) hemicellulose, c) extractives, d) soluble carbohydrates

2. Which plant cell wall most likely has the highest average fiber length:

a) alder; b) bamboo; c) Douglas fir; d) poplar

3. Which of the follow reaction on cellulose does not reduce cellulose DP

a) stop reaction, b) peeling reaction, c) acid hydrolysis, d) base catalyzed hydrolysis

4. How is NaOH recovered from Na₂CO₃ after kraft pulping

a) in the recovery boiler

b) react the green liquor with lime (CaO)

c) during black liquor combustion

d) add lime to black

5. After a typical kraft pulp process:

Most of the lignin is removed from wood

Most of cellulose is removed from wood

Most of hemicelluloses are not removed from wood

Most of wood extractives are removed from wood

Answer 1

1. A. The goal of kraft pulping is to remove the majority of lignin from chips (or other biomass) while minimizing carbohydrate loss. Therefore lignin will be consumed.

2.

3. C. Both the peeling and stopping reaction paces are proportional to the amount of reducing end groups, whereas the rate of alkaline hydrolysis is proportional to the amount of the remaining material. But all these reaction are responsible for reducing cellulose, so the answer is acidic hydrolysis.

4. B. Reaction of green liqur with lime helps to form NaOH from Sodium Carbonate when performing kraft pulping.

5. A. The main reason or objective of kraft process is to break the bonding between the lignin and hydrogen therefore answer is A.